26. BRADFORD HILL CRITERIA

Question 1

1. What is meant by “Analogy”?

Answer 1

• there are other analogues that are observed in the
  literature
• this means that there are many comparisons present
• this is very subjective
• it is not used often

Question 2

2. What is this an example of?

Answer 2

• an association in which analogy is present

Question 3

3. What is meant by “Coherence”?

Answer 3

• the association fits with the known facts of natural
  history of the disease
• it fits in with the pathophysiology of the disease
• these results come from in vitro experiments

Question 4

4. What other criteria is “Coherence” often related to?

Answer 4

• “Plausibility”
• this is why we do not often use “Coherence”

Question 5

5. What is this an example of?

Answer 5

• this is a COHERENT association

Question 6

6. What is meant by “Specificity”?

Answer 6

• the exposure of interest is associated ONLY with the
  outcome of interest
• the exposure cannot be associated with any other
  outcome or disease

NB:
- this criteria does not apply to non-infectious diseases

Question 7

7. What is this an example of?

Answer 7

• this is a Highly Specific Association

Question 8

8. What should we NOT use the Bradford Hill Criteria for?

Answer 8

• they should not use these criteria as definite proof or
  disproof of a Causal Association

THEY SHOULD JUST HELP:
- in deciding on the likelihood of causality
- Bradford Hill stated this himself

Question 9

9. How long ago were the Bradford Hill Criteria published?

Answer 9

• they were published 50 years ago
• some of them are not relevant in modern
  epidemiology
• this means that not all of the criteria are considered

Question 10

10. What does Epidemiologically research aim at investigating?

Answer 10

• it investigates Complex Pathways that lead to diseases

Question 11

11. What can be said about the causes of most diseases?

Answer 11

• they are multi-factorial
• this means that we have many causes for a single
  disease
• the disease is caused by many different risk factors

Question 12

12. What can we assume if we identify a causal association, but the exposure is so rare?

Answer 12

• this exposure will then almost never actually cause the
  outcome we are investigating
• the outcome may actually be caused by another factor
• our exposure could also need other exposures to be
  present in order to cause the outcome

Question 13

13. What is a Necessary Cause?

Answer 13

• the presence of an outcome necessarily implies the
  presence of the cause (exposure)

HOWEVER:
- the presence of the cause (exposure) alone
- does not imply that the outcome will occur

Question 14

14. What is a Sufficient Cause?

Answer 14

• the presence of the cause (exposure) alone can cause
  the outcome

THEREFORE:
- the presence of the outcome does not imply the
presence of the cause (exposure)

Question 15

15. What do we mean when we say that the cause is:
    “Necessary and Sufficient”?

Answer 15

• the cause is always present
• it can cause the disease on its own

Question 16

16. What do we mean when we say that the cause is:
    “Necessary but not Sufficient”?

Answer 16

• the cause is always present
• it cannot cause the disease on its own

Question 17

17. What do we mean when we say that the cause is:
    “Sufficient but not Necessary”?

Answer 17

• the cause is not always present
• it can cause the disease on its own

Question 18

18. What do we mean when we day that the cause is:
    “Neither Necessary nor Sufficient”?

Answer 18

• the cause is not always present
• it cannot cause the disease on its own